US Department of Transportation and international regulations require testing of all chemicals for skin corrosivity, which is defined as destruction of human skin at the site of contact. For safe handling and transportation purposes, each corrosive is assigned a "packing group" designation, which depends on how quickly skin damage occurs. Previously accepted test methods have utilized rabbits to determine packing groups. However, corrosive chemicals are very harsh and can cause considerable discomfort and/or severe pain to the animals. A number of in vitro tests have been developed but none of them adequately meet all of the US regulatory and market needs. The goal of this project will be to utilize a human skin-like in vitro model, EpiDermTM, to develop and validate an in vitro assay to determine skin corrosivity packing groups. Phase I research will determine the assay parameters necessary to differentiate between the 4 corrosivity packing groups. A preliminary prediction model (PM) will be developed using 12 reference chemicals and PM will be tested with an additional 28 test materials. After fine tuning the PM, interlaboratory reproducibility and interlaboratory transferability of the assay will be assessed. Successful completion of the Phase I goals will constitute the pre-validation process for proceeding to formal assay validation studies in Phase II. PUBLIC HEALTH RELEVANCE: Skin corrosivity testing is necessary to insure the safe handling and transport of chemicals. Animal-based test methods suffer from animal welfare concerns and current in vitro methods do not meet all US regulatory requirements. This project will develop an in vitro assay to determine skin corrosivity packing groups and fulfill all testing and regulatory needs. [unreadable] [unreadable] [unreadable]